The present invention relates generally to water flow systems such as for collecting and discharging waste water, storm water and the like, especially wherein water inflow rates may fluctuate widely and unpredictably. More particularly, the present invention relates to a pumping station adapted for use in such water flow systems to effectively discharge widely fluctuating inflows of water.
In water handling systems for conveying waste water, storm water and the like to a treatment station, it is common practice to provide a water pumping station with two pumps of equal size and pumping capacity equivalent at least to a predetermined maximum anticipated head for the water flow system to provide the pumping station with a so-called redundant pumping ability as a safeguard against pump malfunction. That is, even in the event of a malfunction of one of the pumps, the capacity of the remaining pump would still fully satisfy the expected pumping demands placed on the pumping station. In such pumping stations, the pumps are commonly installed in a parallel configuration to permit alternative operation of the pumps, while the non-operating pump remains idle, so that each pump is exercised on a systematic basis. As a guard against unexpected rates of inflowing water, such as may be the result of unusually high storm water or waste water inflows from excessive rain, batch waste water discharges and discharges from pretreatment facilities, etc., a high water indicator and switching arrangement may be provided to detect rates of water inflow exceeding the outflowing capacity of a single operating pump and, in turn, to actuate the idle pump to operate in parallel with the initially-actuated pump to increase the overall pumping capacity of the pumping station.
Disadvantageously, however, the increase in pumping capacity achieved by operating both pumps in parallel is relatively small in relation to the pumping capacity of a single pump. Thus, on such occasions, it is not unusual for such water pumping stations, even when both pumps are operating simultaneously, to be incapable of discharging water as rapidly as it inflows, sometimes causing potentially dangerous backups of water in the associated storm water and/or waste water lines feeding the pumping station. One possible solution to this occasional problem is to select the pumps to be of a sufficiently larger size and capacity than the normally anticipated maximum system head so as to provide sufficient additional reserve pumping capacity to handle occasional water inflow rates exceeding the expected maximum system head. However, this approach to the problem would significantly increase the cost of the pumping station and further would result in even greater underutilization of the pumping capacity of the individual pumps during all normal conditions excepting only occasions when water inflow rates exceed the expected maximum system head.